1. Field of the Invention
The present invention relates to a safety syringe, and more particularly to a safety syringe having a plunger with a hook formed on a distal end of the plunger and a needle hub with a pair of retaining plates one of which has an opening defined to correspond to the hook, so that after the hook extends through the opening and securely engages with a periphery of the opening, the needle hub is able to be driven by the plunger into the barrel.
2. Description of Related Art
With reference to FIG. 9, a conventional safety syringe has a needle hub (70) with a bottom (71) defining therein a Y-shaped channel (72) and a plunger (80) with an arrow head (81) formed on a distal end of the plunger (80) to correspond to the Y-shaped channel (72). It is to be noted that the Y-shaped channel (72) is inclined with respect to an imaginary longitudinal axis of the syringe, such that when the arrow head (81) is received in the Y-shaped channel (72) and the plunger (80) is moving away from the needle hub (70), the needle hub (70) will be driven backward into the barrel (82). Because the Y-shaped channel (72) is inclined relative to the imaginary longitudinal axis of the syringe, after the needle hub (70) is completely pulled back in the barrel (82), the needle (73) together with the needle hub (70) is slantedly received in the barrel (82), such that the needle (73) can not be used again. However, when a solution is received in the barrel (82) and the plunger (80) is pushing forward to the needle hub (70), the approaching of the arrow head (81) to the Y-shaped channel (72) stops the flow of the solution out of the needle (73). The pressure of the remaining solution within the barrel (82) also stops the continuous movement of the arrow head (81) to the Y-shaped channel (72), such that the arrow head (81) can not be received in the Y-shaped channel (72) when in application.
To overcome the shortcomings, the present invention tends to provide an improved safety syringe to mitigate and obviate the aforementioned problems.
The primary objective of the present invention is to provide a safety syringe having a plunger with a head integrally formed on a distal end of the plunger by means of a neck, wherein the head has a hook formed on a sidewall of the head and a slanted face formed oppositely to the hook and a needle hub with a pair of retaining plates one of which has an opening defined to correspond to the hook and a slit defined between the two retaining plates. When the hook is approaching the opening, the remaining solution inside the barrel can still flow through the slit and out of the needle.
Another objective of the present invention is to provide a positioning device to secure the alignment of the hook to the opening during the movement of the plunger, so that a user will not have to rotate the plunger to align the hook to the opening after use.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.